Trail grader



Nov. 14, 1967 H. E. MILLER TRAIL GRADER 2 Sheets-Sheet 1 Filed Nov. 18,1964 v v INYENTOR. fiazaZdfE'Mz Z 6 a. L E

ATTORNEYS NOV. 14, 1967 E 3,352,036

TRAIL GRADER Filed Nov. 18, 1964 l 2 Sheets-Sheet 2 f 5'- 7 A m fl w r WATTORNEYS INVENTOR.

fiQrOZdEMZZZer Patented Nov. 14, 1967 3,352,036 TRAIL GRADER Harold E.Miller, P.0. Box 98, Milwaukee, Wis. 53201 Filed Nov. 18, 1964, Ser. No.412,009 17 Claims. (Cl. 37-108) ABSTRACT OF THE DISCLOSURE A trailgrader having a pair of carriage frames wheel mounted for rolling onspaced rails at the opposite sides of a roadbed and a center beamassembly interconnecting the carriage frames and including a pair oftubular beams of different sizes arranged to slide one within the otherin telescopic relation to accommodate variations in the distance betweenthe carriage frames as the width of the roadbed and the distance betweenthe rails varies. The center beam assembly is vertically adjustable andcompacted stiffening particulate is confined within the smaller tubularbeam to provide rigidity.

This invention relates generally to road building apparatus and moreparticularly to apparatus for preparing roadbed and similar surfacesprior to the laying of concrete, asphalt or similar pavement thereon.

Generally in the construction of roadway such as concrete or asphalthighway, where conditions are such as to require it, a rough grade ofthe ground surfaces is obtained by power tools such as tractors or thelike. Form rails are then placed on both sides of the roadbed andcarefully leveled and spaced in accordance with the requirements of thedesired finished pavement.

In order to provide a final grade for the ground surfaces an apparatusgenerally referred to as a trail grader is employed. The trail grader isplaced on the form rails and rolled therealong by wheels provided forthat purpose. A cutting blade or plate is suspended between the wheelsin a direction transverse to the rails and is pulled by means of a cableassembly or the like along the rails to traverse the roadbed. Thecutting plate is generally segmentally constructed to provide fordesired crown, and the height of the plate with respect to the wheelsand rails is carefully adjusted, the top of the rails usually beingestablished as a point of reference.

In modern highway construction the width of the roadway often convergesor diverges, as for example, in the case of aprons or approaches leadingto the main lanes of a super highway. In the construction of suchapproaches the narrowing of the distance between the form rails shouldconform to the desired width of the pavement, and as a consequence intraversing such approaches for leveling purposes the width of the trailgrader should vary in accordance with the narrowing attitude of the formrails.

In addition, depending on the cutting depth, soil conditions, equipmentcapacity and other factors, it is often necessary to traverse the trailgrader over the ground surfaces more than once, varying the depth of thecutting plate with each successive out until the final finished grade isachieved.

Such considerations make manifest the desirability of providing meansfor easily and continuously changing the width of a trail grader andalso for changing the cut ting depth of the blade with respect to theform rails.

Accordingly, it is an object of the present invention to provide a trailgrader wherein the Width or transverse length of the cutting plate canbe continuously varied to conform to changes in the width of the roadbedor the distance between the form rails.

Another object of the invention is to provide a trail grader havingmeans for easily and continuously changing the height of the cuttingplate with respect to the form rails in order to accommodate variationsin the desired final level of the grade as well as to provide forvariations in cutting depth with successive passes over the groundsurfaces.

Another object of the invention is to provide means for increasing therigidity of the supporting members of the cutting blade or plate.

Another object of the invention is to provide a trail grader havingprovision for continuous adjustment of both cutting width and depth, butwherein the adjust ment apparatus is power operated and controllable bya single operator.

Still another object of the invention is to provide a trail grader ofthe type described which includes a provision for increasing the widthor the transverse length of the cutting blade beyond the normallyavailable width of the cutting blade.

Yet another object of the invention resides in the provision of a manualadjustment mechanism for making rough changes in the setting of thecutting blade height and a pneumatically operated adjustment mechanismfor making fine changes in cutting blade height.

Another object of the invention is to provide a trail grader of the typedescribed which is designed and constructed for heavy-duty applications,is simple to operate, provides for continuous adjustment of cuttingwidth and height, is relatively inexpensive in manufacture and which iscapable of serving a long, useful operating life.

Many-other features, advantages and additional objects of the presentinvention will become manifest to those versed in the art upon makingreference to the detailed description which follows and the accompanyingsheets of drawings, in which preferred structural embodimentsincorporating the principles of the present invention are shown by wayof illustrative example only.

In the drawings:

FIGURE 1 is a perspective view of a trail grader which incorporates theprinciples of the present invention, with portions thereof cut away forclarity;

FIGURE 2 is a fragmentary plan view of the invention illustrating theconnection between a pair of center beam assemblies and a verticaladjustment beam;

FIGURE 3 is similar to FIGURE 2 but includes a beam spacer memberinterposed between the center beam assemblies and the verticaladjustment beam for extension of the center beam assemblies;

FIGURE 4 is a vertical cross-sectional view of the center beamassemblies of the invention and including a beam stiffener member shownpartly in elevation;

FIGURE 5 is a fragmentary plan view of the center beam assembliesconnected at the ends thereof to a pair of vertical adjustment beams;

FIGURE 6 is an elevational side view of the invention with parts removedfor clarity and with a vertical adjustment beam thereof illustrated in araised and in a lowered position; and

FIGURE 7 is a perspective view of the center beam stiffener memberillustrated in FIGURE 4.

As shown in the drawings:

Although the principles of the present invention are of utility in anyroad building apparatus, a particularly useful application is made totrail graders and the illustrative embodiment herein shown at referencecharacter 10 in FIGURE 1 consists generally of a pair of spaced endmembers or carriage frames 11 and 12 interconnected by a center sectionindicated generally at 13.

Each of the carriage frames 11 and 12 comprises an elongated carriagebeam 14, rectangularly shaped in crosssection and having mounted at theends thereof a pair of wheels 16, 16 for engaging and for being rolledalong one of a pair of spaced form rails 17, 17.

In order to mount and to control the height of the center section '13,an elongated vertical adjustment beam 18 is carried on each of thecarriage beams 14. Each of the beams 18 comprises a pair of verticalside plates 19 and 20 and a pair of horizontally extending top andbottom plates 21 and 22. As noted, the vertical adjustment beams arehollow and the horizontal space between the inner surfaces of the sideplates 19 and 20 is substantially equal to the horizontal distancebetween the outside faces of a pair of side plates 23 and 24 of theirrespective carriage beams 14. The vertical distance, however, betweenthe inside face of the top and bottom plates 21 and 22 is considerablygreater than the vertical distance between the outside faces ofcorresponding top and bottom plates 26 and 27 of their respectivcarriage beams such that the vertical adjustment beams are capable ofvertical movement on the carriage beams but are essentially stationaryin a lateral direction with respect to the beams.

As noted situations arise in certain types of pavement construction whenthe roadbed, and accordingly the form rails 17, 17, do not extend inparallel relation, but may converge as, for example, in the constructionof an approach to the main lanes of a super highway. Accordingly, thecenter section 13- of the present invention, which constitutes theactual cutting or grade leveling portion of the invention, istelescopically extensible to accommodate constantly varying widthsbetween the form rails 17, 17 and correspondingly the carriage frames 11and 12.

Accordingly, the center section 13 comprises a pair of center beamassemblies 28 and 29, each of which comprises a pair of tubular orelongated hollow complementarily shaped beams, one of which is larger incrosssection as indicated at 30 and the other of which is smaller incross-section as indicated at 31, with the inside dimensions of thelarger beam and the outside dimensions of the smaller beam being sizedsuch that the smaller beam slides snugly yet freely within the largerbeam in telescopic relation, It will be appreciated that although theillustrative beams which comprise the center beam assemblies arerectangular in cross-section for increased strength, beams having othercross-sectional configurations could also be advantageously utilized.

'The beam assemblies 28 and 29 extend in spaced parallel relationbetween the carriage frames 11 and 12 and it will be noted that theassemblies are in vertical alignment, that is, beam assembly 29 issituated directly ahead of assembly 28 in the direction in which theapparatus 10 moves along the form rails 17, 17 during a levelingoperation.

Connected in fixed assembly to a front face 32 of each of the largerbeams 30 is a downwardly depending slightly forwardly inclined plate orcutter holder 33 which extends transversely along the length of thelarger beam 30 and which is formed with a plurality of horizontallyextending slots 34 at spaced points along the length thereof. Aplurality of eye bolts 35 are threaded, welded or other- Wise securelyfastened to each face of the cutter holders 33 in spaced relation toreceive the ends of cables or the like tension members connected to atractor or other power apparatus for pulling the grader along the rails17, 17.

Attached to each of the cutter holders 33 by means of nut and boltassemblies 36 or other fastening means are a plurality of individualcutting or leveling plates 37, which extend along the length of thecutter holders and which actually engage and level the grade of theground or like surface. The cutting plates 37 are adjustable in theslots 34 in order to accommodate a crown or other transversely irregularcontour of the ground surface. A plurality of bracer plates 38 arewelded to the cutter holder plates 33 and the larger beams 38 at spacedintervals along the length thereof in order to provide additionalstrength to the cutter holders 33.

In order to increase the strength and to minimize bowing in a transversedirection of the center section 13 as the individual center beamassemblies 28 and 29 are in an extended condition, the larger andsmaller beams 30 and 31 of assemblies 28 and 29 are reversed withrespect to their relationship and connection to the carriage frames 11and 12. For example, referring to FIGURE 5 the larger beam 30 of thecenter beam assembly 28 is connected to the carriage frame 11 and thesmaller beam 31 thereof is connected to the carriage frame 12. Sucharrangement is reversed, however, with respect to the center beamassembly 29 such that when the center section 13 is extended a largerbeam 30 of at least one of the assemblies 28 and 29 is intersected by atransversely extending plane at all points along the entire length ofthe center section 13.

It will be apparent that the larger beams 30 have an increased rigidityfactor with respect to the smaller beams 31 which are telescopicallyreceived therein and in order to increase the rigidity of the smallerbeams 31 to more closely approximate that of the larger beams 30 thesmaller beams may be filled completely or at certain portions thereofwiht compacted particulate matter such as sand, fine gravel or the likeas indicated at reference numeral 39 in FIGURE 4. Such particulatematter also increases the mass of the center section 13, such additionalmass being particularly advantageous when preparing relativelyunyielding or hard surfaces, such as hard clay, to oppose a tendency ofthe grader to raise or climb as the cutting plates engage such hardsurfaces.

In order to further reduce transverse bowing of the center section 13,particularly when the section is extended and the ground or soilconditions or the likes are extremely hard, means are provided tointerconnect the center beam assemblies 28 and 29 in locked-togetherrelation.

Referring to FIGURES 4 and 7, a beam connector or stiffener bar 40which, in the illustrated embodiment, comprises a short, hollow,rectangularly shaped beam, is provided with a pair of spaced tubularstubs 41 and 42 depending downwardly therefrom. A tubular sleeve 43having an outer diameter substantially equal to the transverse orlateral distance between the larger beams 30 of the assemblies 28 and 29is connected in fixed assembly to a back face 44 of the larger beam 30of the assembly 29, as for example, by means of a weld 46.

When the stiffener bar 40 is mounted in place, the stud 42 thereof,which has an outer diameter substantially equal to the inner diameter ofthe sleeve 43, is inserted downwardly into the sleeve, the other stud 41being slipped downwardly over a back face 46 of the assembly 28. Thedistance between studs 41 and 42 and the diameters there of are suchthat when the stiffener bar 40 is mounted in position the beamassemblies 28 and 29 are locked together" in a transverse direction. Itwill be appreciated that more than one stiffener bar can be mountedacross the portions of the beam assemblies 28 and 29 having overlappinglarger beams, and in addition the bars 40 can be arranged anddimensioned to be effectively utilized even along portions of the beamassemblies 28 and 29 wherein the larger beams 30 thereof do not overlap.Such arrangement would, of course, lock the larger beam of one centerbeam assembly with the smaller beam of the other center beam assembly.

Referring to FIGURES 1 and 2, the beam assemblies 28 and 29 are securedto the carriage frames 11 and 12 in the illustrative embodiment in thefollowing manner. Corresponding ends of a larger beam 30 and a smallerbeam 31 adjacent one of the carriage frames is secured in fixed assemblyby means of a weld connection or the like to a flat vertical beamsupporting plate 48 removably mounted on a complemental flat verticalcarriage plate 49 by means of a plurality of fasteners such as thethreaded bolts at 50. The carriage plate 49 is connected in fixedassembly to the side plate 20 of the vertical adjustment beam 18.

In order to extend the length or the transverse width of the centersection 13 beyond the permissible telescopically extensible lengththereof, a beam spacer member indicated generally at reference character51 in FIGURE 3 may be inserted between the beam supporting plate 48 andthe carriage plate 49. The spacer member 51 is more particularlycharacterized as comprising a pair of spacer beams 52 and 53 alignedgenerally coaxially with the beams of the respective center beamassemblies 28 and 29 and dimensioned in a longitudinal direction inaccordance with the desired additional length requirements of the centersection 13. A pair of spacer plates 54 and 56 are welded at the ends ofthe spacer beams 52 and 53 and are joined, respectively, to the beamsupporting plate 48 and the carriage plate 49 by fastener members 57.

In order to provide full width cutting effect of the center section 13with the spacer member 51 incorporated therein, a cutter holder 33 andcutting plate 37 are attached to the front spacer beam 53.

As noted, one of the features of the invention resides in the provisionof means for continuously varying the width of the center section 13 toconform to changes in width of the form rails 17 and to that end adualacting hydraulic cylinder 58 is mounted on the top face of thelarger beam 30 of the forward center beam assembly 29. A telescopicallyextensible piston member 59 is connected at a distal end 60 thereof tothe beam supporting plate 48 of the carriage frame 11.

A pair of conduits 61 and 62 communicate opposite ends of the cylinder58 with a source of pressurized fluid which, in the illustratedembodiment, comprises a motorpump assembly 63 mounted on a platform 64which may be connected in fixed assembly both to the larger beam 30 ofthe forward beam assembly 29 and to the side plate 20 of the verticaladjustment beam 18 mounted on the carriage frame 12.

A control box 66 includes a plurality of control levers 67 which may bemounted in the conduits 61 and 62 for actuating the cylinder 58. A covermember 68 may be mounted on the beam assembly 29 in order to house thehydraulic cylinder for purposes of protection.

As noted, the beam assemblies 28 and 29 are connected to the verticaladjustment beams 18 by means of the beam supporting and carriage plates48 and 49. In order to provide vertical adjustability for the beamassemblies means are provided for pivoting the vertical adjustment beams18, 18 upwardly and downwardly as well as for adjusting the fulcrum orpivotal point of the beams.

As best illustrated in FIGURE 6, a pin and port arrangement is situatednear one end 68 of the vertical adjustment beam 18 and comprises aplurality of vertically spaced ports 69 which extend horizontally acrossthe width of the beam 18. A single complementarily shaped port 70 isformed in the carriage beam 14 and is alignable with any of the ports 69for receiving a pin 71 to maintain the end 68 of the beam 18 in adesired position of adjustment and for providing a fulcrum for the beam18.

An opposite end 72 of the beam 18 is interconnected to the carriage beam14 by means of a hydraulic cylinder 73 pivotally connected at a lowerend 74 thereof to the carriage beam 14 and at an upper end 76 thereof toa web flange 77 which is welded or otherwise permanently affixed to thebeam 18. A pair of conduits 78 and 79 communicate pressurized fluid fromthe motor-pump assembly 63 to the cylinder 73 through actuating controllevers as at 67 on the control box 66.

It will be appreciated that the pin and port adjustment arrangement asmanifested by the ports 69 and the pin member 71 can be utilized for arough adjustment in height of the vertical adjustment beams 18 (andcorrespondingly the height of the center beam assemblies 28 and 29) andthe hydraulic cylinder 73 can be utilized for fine adjustment.

Not infrequently, after the cutting depth of the cutting blades 37 hasbeen carefully adjusted with respect to the elevation of the form rails17, the top surfaces of which are generally established as anelevational reference point, more than one pass over the ground surfacemust be performed in order to obtain a close tolerance grade. In suchcircumstances, after the trail grader has traversed a section of theroadbed it is moved back for another cut or over the section. It isadvantageous, during such backward travel, to raise the cutting platesaway from the ground surfaces. 3

Generally any change in vertical disposition of the cutting platesrequires a complete readjustment when the cutting plates are againlowered to their proper cutting height. In order to avoid the necessityfor such readjustment the present invention includes means enabling thecutting plate to be raised above the ground surface and then loweredagain to its predetermined cutting height without readjustment thereof.

Thus, a vertical threaded stop stud 80 is mounted in a complementarilythreaded member of the vertical adjustment beam 18 as, for example, thetop plate 21 thereof, and can be adjusted such that after the beam 18has been pivoted to an upward position as indicated by the dashed linesin FIGURE 6 by means of the hydraulic cylinder 73, and is to be loweredagain to a cutting position as indicated by the solid lines of FIGURE 6,a lower end portion 81 thereof will abut the top plate 26 of thecarriage beam 14 to thereby prevent further downward movement of thebeam 18. Consequently once the stop stud is adjusted to provide aworking or cutting height of the cutting plate 37, the verticaladjustment beam 18 can be raised and lowered successively without againmaking reference to the elevation of the form rails 18 while maintaininga predetermined cutting elevation in its lower portion. Of course, achange in position of the pin members 71 with respect to the ports 69 atthe opposite ends of the beams 18 would necessitate a readjustment ofthe beam 18 and the cutting plates 37 by again making reference to theelevation of the form rails 17.

As best seen in FIGURE 1, the wheels 16 may be provided with axiallyspaced flanges 82, 82 at the side faces thereof for guiding the wheelsalong the top surfaces of the form rails, particularly in circumstanceswhere the form rails do not extend in parallel relation but insteadslightly converge or diverge as, for example, in super highway approachconstruction.

Although minor modifications might be suggested by those versed in theart, it should be understood that I wish to embody within the scope ofthe patent warranted hereon all such modifications as reasonably comewithin the scope of my contribution to the arts.

I claim as my invention:

1. A trail grader for preparing roadbed and the like surfacescomprising:

a pair of spaced carriage frames each provided with wheels for riding onspaced form rails,

-a center beam section comprising a pair of elongated,

tubular center beams arranged one within the other in mutuallytelescopic relation with each being connected at one end thereof to oneof said carriage frames,

cutting plates affixed to said center section for engaging and preparingsuch roadbed, and

dual-acting power means interconnecting said center beams to provideselective telescopic change in overall length thereof and to control thespacing of said carriage frames to conform to the spacing of the trails.

2. A trail grader for preparing roadbed and the like surfacescomprising:

a pair of carriage frames each provided with wheels for riding on one ofa pair of spaced substantially parallel rails,

a center beam section comprising a pair of elongated center beamassemblies extending transversely between the rails and interconnectingsaid carriage frames,

said center beam assemblies being vertically aligned and transverselyspaced with each of said assemblies comprising:

a pair of tubular center beams arranged one within the other in mutuallytelescopic relation,

each of said center beams being connected at opposite ends thereof tosaid carriage frames,

cutting plates affixed to each of said center beam assemblies forengaging and for preparing such roadbed, and

dual-acting power means interconnecting said center beams of at leastone of said assemblies to selectively telescopically actuate said oneassembly for controlling the spacing of said carriage frames to conformto the spacing of the rails.

3. A trail grader for preparing roadbed and the like surfacescomprising:

a pair of carriage frames each provided with wheels for riding on spacedsubstantially parallel form rails,

a center mean assembly comprising a pair of hollow center beamsinterconnecting said carriage frames and extending transversely to suchrails,

one of said beams being undersized to be telescopic-ally received in theother of said beams for varying the spacing between said carriageframes, and

compacted particulate matter in said undersized beam to increase therigidity thereof with respect to the other beam.

4. A trail grader for preparing roadbed and the like surfacescomprising:

a pair of carriage frames each provided with wheels for riding on spacersubstantially parallel form rails,

a center beam assembly comprising a pair of elongated hollowrectangularly shaped telescopically arranged center beams extendingtransversely between said carriage frames and connected at opposite endsof the center section to the adjacent carriage frames,

cutting plates aflixed to the larger of said center beams for engagingand for preparing said roadbed, and

a quantity of particulate matter compacted in the smaller of said centerbeams to increase the rigidity thereof.

5. A trail grader comprising:

a pair of carriage frames adapted to move along a pair of form rails,

a pair of center beam assemblies extending transversely between saidcarriage frames in spaced parallel relation,

each of said assemblies comprising a pair of elongated telescopicallyarranged center beams having overlapping inner ends and outer endsadjacent respectively said carriage frames,

means including an elongated beam spacer member to be interposed betweenthe beam assemblies and one of said carriage frames to effectivelyincrease the length of said center beam assemblies, and

fastening means to detachably connect said center beam assemblies andsaid beam spacer member to said carriage frames for quick assembly anddisassembly of the grader and for selectively increasing the effectivewidth thereof with said beam spacer member.

6. The trail grader as defined in claim 5 and including cutting platesaffixed to said center beam assemblies and to said beam spacer memberfor engaging and for preparing a roadbed surface along the entire lengthof said extended center beam assemblies.

7. A trail grader comprising:

a pair of carriage frames adapted for movement along spacedsubstantially parallel form rails, and

a pair of center beam assemblies extending transversely between saidcarriage frames,

each of said assemblies comprising:

an elongated larger hollow beam connected to one of said carriageframes, and

a complementary elongated smaller hollow beam connected to the other ofsaid carriage frames and received in telescopic relation by itscorresponding larger beam for widening the space between said carriageframes,

said beam assemblies being reversely arranged with respect to saidcarriage frames so that each of said carriage frames has a larger beamof one center beam assembly and a smaller beam of the other center beamassembly connected thereto to more nearly equalize the combined strengthrigidity of the beam assemblies along the lengths thereof to minimizetransverse bowing of the assemblies under load.

8. The trail grader as defined in claim 7 and including a quantity ofparticulate matter compacted Within each of said smaller beams toincrease the overall rigidity of said center beam assemblies.

9. A trail grader to be moved along a pair of substantially parallelform rails to prepare roadbed and the like surfaces comprising:

a pair of carriage frames each including:

an elongated carriage beam extending parallel to its corresponding rail,

wheels mounted on said carriage beam for moving said carriage framealong its rail, and

an elongated vertical adjustment beam extending in juxtaposition to saidcarriage beam,

an elongated telescopically arranged center beam assembly extendingtransversely between said carriage frames and connected at the endsthereof to said vertical adjustment beams, and

mounting means for vertically movably mounting said vertical adjustmentbeams on their respective carriage beams and including means forselectively adjusting the vertical disposition of said verticaladjustment beams with respect to said carriage beams while said graderis in movement along the rails to correspondingly adjust the height ofthe center beam assemblies with respect to the rails.

10. A trail grader to be moved along a pair of form rails to prepareroadbed and the like surfaces comprising:

a pair of carriage frames each including:

an elongated carriage beam extending parallel to its respective rail,

wheels mounted on said carriage beam for moving said carriage framealong its form rail,

an elongated vertical adjustment beam extending along said carriagebeam,

a center beam assembly extending transversely between said carriageframes and connected at the ends thereof to said vertical adjustmentbeams intermediate the ends thereof,

means at one end of each of said vertical adjustment beams to pivotallyconnect said one end to its respective carriage beam, and

means at the opposite end of each of said vertical adjustment beams toprovide selective vertical adjustment of said opposite end with respectto its corresponding carriage beam to pivot said vertical adjustmentbeams to vary the height of said center beam assembly with respect tothe form rails.

11. In a trail grader,

a pair of carriage frames each comprising:

an elongated carriage beam having Wheels mounted thereon for ridingalong one of a pair of spaced form rails,

a pair of elongated vertical adjustment beams extending, respectively,in juxtaposition to said carriage beams,

means providing cooperating pin and port means on said carriage beam andon said vertical adjustment beam at one end thereof to provide verticaladjustment and vertical pivotal movement of said vertical adjustmentbeam,

hydraulic cylinder means at the opposite end of said vertical adjustmentbeam to vary the height of the opposite end thereof with respect to saidcarriage beam,

a center beam assembly extending between said carriage frames andconnected at the ends thereof to said vertical adjustment beams, and

cut-ting plates affixed to said center beam assembly for engaging andfor grading roadbed and the like surfaces.

12. In a trail grader,

a pair of carriage frames each comprising:

an elongated horizontally extending carriage beam having wheels mountedthereon for rolling along a form rail,

an elongated vertical adjustment beam extending in juxtaposition to saidcarriage beam,

pin means for pivotally connecting said vertical adjustment beam at oneend thereof to said carriage beam,

power means interconnecting said carriage beam and said verticaladjustment beam to provide vertical pivotal movement of said verticaladjustment beam about said pin means, and

cooperating threaded stud and flange means on said carriage beam and onsaid vertical adjustment beam to provide a stop to limit the downwardpivotal movement of said vertical adjustment beam with respect to saidcarriage beam,

a center beam assembly extending between said carriage frames andconnected at the ends thereof to said vertical adjustment beams, and

cutting plates afiixed to said center beam assembly for engaging and forgrading roadbed and the like surfaces.

13. The trail grader as defined in claim 12 wherein said verticaladjustment beam is hollow and has a given inside vertical dimensiongreater than the outside vertical dimension of said carriage beam andhas an inside horizontal dimension substantially equal to the outsidehorizontal dimension of said carriage beam and wherein said carriagebeam extends longitudinally through said vertical adjustment beam toprovide vertical movement of said vertical adjust-ment beam whilerestricting lateral movement thereof.

14. In a trail grader for preparing roadbed and the like surfaces,

a pair of carriage frames each comprising:

an elongated horizontally extending carriage beam,

wheels mounted on said carriage beam for rolling along one of a pair ofspaced form rails,

an elongated vertical adjustment beam extending in juxtaposition to saidcarriage beam,

pin means pivotally connecting said vertical adjustment beam at one endthereof to said carriage beam, and

a first hydraulic power cylinder pivotally connected at the respectiveends thereof to said carriage beam and to said vertical adjustment beamto provide pivotal movement of said vertical adjustment beam withrespect to said carriage beam about said pin means,

a telescopically extensible center beam assembly extending transverselybetween said carriage frames and connected at opposite ends thereof tosaid vertical adjustment beam,

a second hydraulic power cylinder mounted on said center beam assemblyto vary the length thereof, and

fluid pressure means for connecting a source of pressurized fluid tosaid hydraulic power cylinders including control means for continuouslycontrolling the vertical adjustment and the length of said center beamassembly while said trail grader is moved along the form rails toaccommodate changes in desired width and depth of such roadbed.

15-. The trail grader as defined in claim 14 and including axiallyspaced flanges on said wheels to maintain said wheels on said form railsupon changes in the length of said center beam assembly.

16. A trail grader for preparing roadbed and the like surfacescomprising:

a pair of spaced carriage frames each provided with wheels for riding onspaced form rails,

a pair of telescopically extensible spaced parallel vertical alignedtransversely extending center beam assemblies interconnecting saidcarriage frames,

cutting plates on said center beam assemblies for engaging and forgrading such roadbed, and

means for stiffening said widening beams against bowing under atransverse cutting load comprising:

a horizontal stiffener bar extending transversely between said centerbeam assemblies, and means on said stiffener bar for engaging andmaintaining said center beam assemblies in lockedtogether relation.

17. A trail grader for preparing roadbed and the like surfacescomprising:

a pair of spaced carriage frames each provided with Wheels for riding onspaced form rails,

a pair of horizontally transversely extending vertically aligned centerbeam assemblies interconnecting said carriage frames,

said beams being horizontally spaced from one another a given distancein the direction transverse to said beams,

cutting plates on said beams for engaging and for grading such roadbed,and

means for stiffening said beam assemblies against bowing under atransverse cutting load comprising:

a horizontally disposed stiffener bar extending transversely to saidbeam assemblies,

a pair of tubular studs depending downwardly from said stiffener bar,

one of said studs being situated between the interfaces of said beamassemblies and having a given outside diameter,

a tubular sleeve connected in fixed assembly to the interface of one ofsaid beam assemblies and having an outside diameter substantially equalto said given space and an inside diameter sized to receive said one ofsaid studs in snug telescopic relation, and

the other of said studs being transversely spaced from said one stud tosnugly abut the outside 11 face of the other of said beam assemblies toconnect said beam assemblies in locked-together relation.

References Cited UNITED STATES PATENTS 413,846 10/1889 Chambers 371081,833,546 11/1931 Wight 37-108 12 1,949,151 2/ 1934 Fanfarillo 371082,965,987 12/1960 Graves 37--108 2,973,723 3/1961 Hudis et al. 9445 X3,261,271 7/1966 Tomaso 9445 ABRAHAM G. STONE, Primary Examiner.

R. L. HOLLISTER, Assistant Examiner.

1. A TRAIL GRADER FOR PREPARING ROADBED AND THE LIKE SURFACESCOMPRISING: A PAIR OF SPACED CARRIAGE FRAMES EACH PROVIDED WITH WHEELSFOR RIDING ON SPACED FORM RAILS, A CENTER BEAM SECTION COMPRISING A PAIROF ELONGATED, TUBULAR CENTER BEAMS ARRANGED ONE WITHIN THE OUTER INMUTUALLY TELESCOPIC RELATION WITH EACH BEING CONNECTED AT ONE ENDTHEREOF TO ONE OF SAID CARRIAGE FRAMES, CUTTING PLATES AFFIXED TO SAIDCENTER SECTION FOR ENGAGING AND PREPARING SUCH ROADBED, AND DUAL-ACTINGPOWER MEANS INTERCONNECTING SAID CENTER BEAMS TO PROVIDE SELECTIVETELESCOPIC CHANGE IN OVERALL LENGTH THEREOF AND TO CONTROL THE SPACINGOF SAID CARRIAGE FRAMES TO CONFORM TO THE SPACING OF THE RAILS.